1、中國科學技術大學碩士學位論文高溫動態(tài)拉伸下NGTiAl彈塑性力學行為的數值模擬姓名：王東申請學位級別：碩士專業(yè)：固體力學指導教師：李子然昝祥20090601ABSTRACTTheexcellentmechanicalbehaviorofTiAIintermetallicsatelevatedtemperaturemakesitapossiblenewgenerationstructurematerialservmgasaeronauti

2、calmaterialConsideringtheworkingenvironmentofaerospacevehiclesthecapabilityofsufferingimpactloadingsisrequiredSoitishighlyilnponantt0researchonthedyn鋤icmechanicalpropertiesofTiAlintermetallicsatelevated鋤∞er秈eThedynamicex

3、perimentatelevatedtemperaturehasmanydifficultlestillnow’soitisnecessarytoconstructapropermodeltosimulatethedyn撇1cmechanicalbehaviorofTiAlatelevatedtemperatureInthisStudy，basedonratedependentcrystalplasticitytheorytheTiAl

4、singlecrystalconstitutiveequation，whichincorporatestheinfluenceoftemperatureandtheefrectsofbothdislocationslipa11ddeformationtwinning，isconstructedArevisedevolutionequationoftwinningissuggestedbyintroducingthesaturate徹ml

5、ingvolumefractionOnthebasisofthesinglecrystalconstitutiveequation，apolycrystallinemodelwhichcomainsenou曲randomlyorientatedelementsisconstructedThentheelastoplasticbehaviorofNGTiAlissimulatedatdifferenttemperature(Roomtem

6、peratuIle～840“C)anddifferenttensilestrainrate(1031350Sq)ThecalculationresultsShowthatthesimulatedcurvesareconsistentwithexperimentalones，thallStheappliedconstitutiveequationsandthepolycrystallinemodelCallwelldescribethem

7、ateriaIs，temperatureandstrainratedependenceandwork。hardeningbenaVlorBesides，thecontributionsofdislocationslipanddeformationtwinningtothe口lasticdefomationofNGTiAlareinvestigated’TheresultsshowthatbothⅡlechallismsarethemaj

8、orplasticdeformationmechanismsofNGTiAlDynamic10adingismorepropitioustotheoccurrenceofdeformationtwinningHowevertheinfluenceoftemperanlreonbothmechanismsisnotobviousIntheprocessofplasticdeformation，晰砸ngispredominantattheb

9、eginningofplasticdeformationHoweverwiththeincreasingplasticstrain，thecontributionofdislocationmovementincreasesandCOdevelopswithtwinningatlastKeywords：TiAIintermetallics；deformationmechanism；dynamictensile；polycrystallin